17. Which of the following is the best proposition to be filled in the blank?
(A) of
(B) to
(C) against
(D) upon

be of + noun用法

1. be of 後可接value, importance, use, help, significance, interest, benefit 等一些抽象名詞，這樣的結構用來說明句子主語所具有的作用、重要性或意義。 在這類抽象名詞前我們可用一些形容詞，如: great, little, some, any, no, not much等來修飾抽象名詞，用以說明程度。如:

They are of great help to learners of English.

他們對英語學習者有很大幫助。

The book will be of great value to students of history.

這本書對學歷史的學生將很有用。

The meeting is of great importance.

這個會議很重要。

This medicine is of no use.

這種藥無效。

This matter is of no significance.

這件事無關緊要。

2.在「be of + 抽象名詞」結構中， 其意義就相當於 「be + 與該抽象名詞同詞根的形容詞」。如：be of value→be valuable, be of help→be helpful, be of use→be useful, be of importance→be important, be of significance→be significant等。它們之間可以相互轉換， 因此，以上各例句可轉換為：

They are very helpful to learners of English.

This book is very valuable to students of history.

This meeting is very important.

This medicine is useless.

This matter is insignificant.

2. be of +名詞，還可用來說明句子主語在度量，大小，顏色，類別等方面的特徵。這類名詞有 colour, age, size, height, weight, shape, type，kind, quality等。在這類名詞前常用different, all, the same， this, that, a(n) + 形容詞等詞來修飾或說明。如：

Coins may be of different sizes, weights, shapes, and of different metals.

貨幣可能在大小、重量、形狀和鑄造的金屬方面都有所不同。

These pens are of many different colours.

這些筆有許多不同的顏色。

The two rooms are of a size / of the same size.

這兩個房間大小一樣。

He is of the same weight as his brother.

他和他弟弟一樣重。

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